diff --git a/aleksis/apps/chronos/frontend/components/calendar_feeds/details/LessonDetails.vue b/aleksis/apps/chronos/frontend/components/calendar_feeds/details/LessonDetails.vue
index ff840b273735df6bbe18104d88f5c7560bb839fd..6fe521976315b34c4430ebe21b3bfef7828fc28a 100644
--- a/aleksis/apps/chronos/frontend/components/calendar_feeds/details/LessonDetails.vue
+++ b/aleksis/apps/chronos/frontend/components/calendar_feeds/details/LessonDetails.vue
@@ -163,6 +163,13 @@ export default {
             value: "comment",
           },
         ],
+        default: {
+          subject: "",
+          teachers: [],
+          rooms: [],
+          cancelled: false,
+          comment: ""
+        },
       },
     };
   },